The great engagement ring riddle: Kate Bosworth continues to wear a gold band on her wedding finger... but now flashes a large diamond

Since announcing her engagement, Kate Bosworth continues to wear a simple gold band on her wedding ring finger.

While the jewelry is a clear statement of her commitment to fiance Michael Polish, who also has a matching band, the actress stepped out with a giant diamond rock on her other hand last night.

The 29-year-old wore the vintage-inspired ring on her right hand, with speculation that the pretty jewel could be her actual engagement ring.

Ring riddle: Newly engaged Kate Bosworth wore a gold band on her wedding finger, but also flashed a large diamond on her right hand as she attended an event with fiance Michael Polish last night

The couple attended musician Paul Banks' discussion of his new EP Julian Plenti Lives... at Sonos Studio in Los Angeles.

With their arms wrapped around each other, they showed off their matching gold bands.

Official engagement ring? The pretty vintage-inspired ring sat on her middle finger

Kate, as always, looked gorgeous wearing a simple black short-sleeve mini dress and a small matching handbag over her shoulder.

Meanwhile, Michael was handsome in a denim shirt and black trousers.

While engagement announcements are often made by Hollywood stars via statements through their representatives, Kate chose a very different way to let the world know that she was engaged to her boyfriend of one year.

The actress let slip that she was a bride-to-be by referring to the director as her 'fiance' during a recent blog post.

The Superman Returns star was writing about the couple's recent trip in May to South Korea on Vogue.com for their Summer Travel Diaries feature.

'On our first day in Seoul, my fiance, Michael Polish, and I venture out to discover Changdeokgung Palace,' she wrote, before describing their visit in full.

The couple's overseas trip came before they celebrated their one year anniversary together this month.

The pair met on the set of their movie Big Sur, in which Michael directed the gorgeous blonde in the film, which is due out later this year.

Set to be married: Kate announced that she was engaged to Michael this month

Committed: The actress has been wearing her gold band for several months, even before she announced her big news

The couple then made their debut as a
couple at a Coldplay concert last August, and she later gushed to the
Sunday Times Style Magazine over Polish.

Smitten: The pair pose at a Calvin Klein party in Seoul, South Korea in May

'He's a special one. There's nobody in the world I admire or respect more,' she said.

'When I look at him, it's not a crazy infatuation, it's more like we are each other's life partners.'

Kate
has been notoriously quiet about her personal life since her
high-profile relationship with Orlando Bloom, to whom she was also
engaged to.

The star began seeing the Twin Falls Idaho director shortly after splitting with True Blood hunk Alexander Skarsgård last July.

Kate and Micheal recently filmed a short video together in Mexico, to promote Kate's collection for Jewel Mint.

She tweeted: '@michael_polish and I
shot this film in Tulum, Mexico. We felt the tropical feeling reflects
the months @jewelmint pieces.'

The video shows the actress wandering around the streets of Tulum before going for a swim in the clear blue ocean.

Michael directed Kate in the film, and their loving relationship is evident as she gazes directly into the camera.

Polish, whose profile is most certainly on the rise after bagging such a well-known partner, is starting to see his career really take off.

The California native, who has worked on just a handful of films including For Lovers Only, is rumoured to be attached to new film 18 Wheel Butterfly, set to star Evan Rachel Wood.

This new move could see the director’s career skyrocket, giving him a major step-up in the film industry and making him almost as famous as his other half.

Kate seems to have finally found her perfect partner, although a date is yet to be announced for what is set to be a star-studded wedding.

The blonde Superman Returns star seems to be having some well-deserved down time before she promotes her new film Movie 43, which comes out next year.